We propose to characterize antigenic determinants on the surfaces of neural crest and crest-derived neurons using a battery of antibodies produced by hybridoma clones isolated in our lab. We further propose to characterize cell surface alterations that accompany crest cell differentiation and changes in crest cell morphogenetic behavior. We will also pursue our analysis of the cell surface components involved in interactions of crest cells with extracellular matrix macromolecules, and with other cells during morphogenesis and differentiation. In particular, we hope to examine the surface constituents involved in neuron/glial interaction leading to glial cell differentiation. Finally, we will procede with our analysis of mouse mutants affecting the morphogenetic behavior of neural crest cells. To this end, we will employ microspectrophotometric measurements of local differences in the amounts and kinds of GAG and other macromolecules in crest migratory spaces in normal and mutant embryos.